STING Pathway Activation Stimulates Potent Immunity against Acute Myeloid Leukemia

Type I interferon (IFN), essential for spontaneous T cell priming against solid tumors, is generated through recognition of tumor DNA by STING. Interestingly, we observe that type I IFN is not elicited in animals with disseminated acute myeloid leukemia (AML). Further, survival of leukemia-bearing animals is not diminished in the absence of type I IFN signaling, suggesting that STING may not be triggered by AML. However, the STING agonist, DMXAA, induces expression of IFN-β and other inflammatory cytokines, promotes dendritic cell (DC) maturation, and results in the striking expansion of leukemia-specific T cells. Systemic DMXAA administration significantly extends survival in two AML models. The therapeutic effect of DMXAA is only partially dependent on host type I IFN signaling, suggesting that other cytokines are important. A synthetic cyclic dinucleotide that also activates human STING provided a similar anti-leukemic effect. These data demonstrate that STING is a promising immunotherapeutic target in AML. [Display omitted] •Unlike solid cancers, a type I IFN response is not triggered in AML-bearing hosts•STING activation induces expression of IFN-β and other inflammatory cytokines•STING activation promotes DC maturation and leukemia-specific T cell priming•Enhanced immunity translates into prolonged survival in mice with AML Curran et al. demonstrate that, in contrast to solid cancers, a host type I IFN response is not triggered in leukemia-bearing hosts. However, induction of type I IFN and other inflammatory cytokines through STING pathway activation results in potent leukemia-specific immunity, culminating in prolonged survival of mice with AML.